Tremolo-meter.



PATENTED FEB. 11, 1908.

0. P. DOLAN. TREMOLO METER. APPLICATION FILED JUNE 8, 1907'.

CHARLES P. DOLAN, OF BOSTON, MASSACHUSETTS.

TREMOLO-METER.

Specification of Letters Patent.

Patented Feb. 11, 1908.

Application filed June 8. 1907. Serial No. 377.915.

T0 allwhom it may concern:

Be it known that 1, CHARLES P. DOLAN, a citizen of the United States,and resident of Boston, county of Suffolk, State of Massachusetts, haveinvented an Improvement in Tremolo-Meters, of which the followingdescription, in connection with the accompanying drawing, is aspecification, like letters on the drawing representing like parts.

This invention has for its object the production of an instrumentdesigned specifically for use in teaching piano tuning, to assist thestudent in learning and memorizing the different rates of speed and thegraduation of the same which re resent the different number ofvibrations o' the tones essential to a third or sixth in the perfecttemperament. The tremolo system of setting the temperament of a piano isalso known as the Ohickering method, and is the only positive proof bymeans of which the tuner can be assured that the fourths and fifths aretuned properly.

If the fourths and fifths were tuned perfectly in setting a temperamentthe tremolo system as a proof of the correctness of the work would haveno value, but in order to set a perfectly uniform scale in the octavewithin which the temperament is laid, whether it be the octave of O orthe octave of F, the fourths and fifths must be shaded or tunedimperfectly, some being tuned a certain number of vibrations on thesharp side and some on the flat side of the smooth or perfect tone.'Were all of the fourths and fifths tuned perfect or smooth the lastfourth or fifth to be tuned would be very rough and would contain all ofthe vibrations that should be distributed among the other fourths andfifths, each one containing its proper share of the vibrations until therough fourth or fifth, termed the wolf in the temperament, contains onlyits proportionate share. WVhen the fourths and fifths are tuned properlythe intervals of the thirds and sixths will contain vibrations whichwill beat at a rate of speed called a tremolo. When the temperament islaid between the middle octave of F and F these tremolos will graduatein speed from the third of F and A, which is the lower and slowestthird, to the third of O and E, which is the upper and fastest third,each succeeding third up from the third of F and A being somewhatfaster.

The value of the tremolo system is manifest when it is remembered thatif the speed of the beat'of any third is too fast or too possible toaccurately count the relative number of vibrations between the fourth orfifth, and were it not for the tremolos of the thirds and sixths itwould be mere guesswork to attempt such counting. If, however, the tunerthoroughly understands and can recognize the rates of speed required inthe tremolos of the thirds and sixths it is immaterial how many falsewaves the fourth or fifth contains, and my present invention assists thetuner in acquiring readily and accurately the understanding of the ratesof speed required in the tremolos of the thirds and sixths, and impartsthe ability to recognize the same. v

The tremolo meter forming the subject matter of my present invention isconstructed and regulated to such a point of accuracy as will give tothe user a correct conception of the vibrations between the intervals ofthe temperament from the beat of the low or slowest tremolo up to thehigh or fastest tremolo.

The various novel features of my invention will be fully described inthe subjoined specification and particularly pointed out in thefollowing claims.

Figure 1 is a front elevation of a tremolo meter embodying one practicalform of my invention; Fig. 2 is a view of the mechanism contained withinthe casing, the front thereof having been removed Fig. 3 is an enlargedface view of the index or dial on which the tremolos are indicated.

The apparatus isinclosed within a suitable casing (1, having a frontplate a, omitted in Fig. 2, the latter having attached to it an I indexor dial a to be referred to more particularly hereinafter, the frontplate being held in place by suitable screws a Fig. 1.

Within the casing is fixedly secured the motor mechanism and thesounding instrumentality, the former being substantially a clock trainof usual construction and herein comprising a strong spring motorindicated at M, Fig. 1, connected by a suitable train of gears with anescapement wheel 6, and a 00- operating pallet or ratchet partly shownat b and mounted on a rock-shaft b The escapement wheel is veryaccurately cut so that there will be no variation in its teeth, and theratchet b is made with care to release the escapement wheel withabsolute uniformity.

I employ a very powerful spring in the motor M in order that theapparatus may run a sufficient length of time without causing anyvariation in speed due to the diminution in the motive force of thespring, the motor being wound by a suitable key applied to the arbor m,the latter being accessible through the front plate a by means of theaperture a Fig. 1. Upon the escapement shaft 6 I secure a suitabletapper or hammer 0, adapted to cooperate with and strike a soundingboard d of metal or other suitable material, herein shown as mounted onthe frame work L of the clock train in an adjustable manner by aset-screw d. As the escapement wheel I) is rotated by the spring motorthe ratchet b and its supporting shaft oscillates and the tapper 0 willbe vibrated at a rate of speed determined by the regulating orcontrolling means, to be described, the tapper striking upon thesounding board at each vibration.

I have herein shown the speed of the escapement regulated by anadjustable pendulum,

comprising a rod 6 fixedly secured to and depending from the front endof the shaft b extended forward through the frameL, and

I a bob or weight e longitudinally movable upon the oscillating memberor rod 6. A stop collar e on the lower end of the latter limits downwardmovement of the weight and prevents it from accidentally droppingManifestly the position of the weight upon the rod (2 determines theeffective length of the regulator or pendulum, the lower the weight theslower the oscillations, and vice versa, the highest number ofoscillations corresponding to the dotted line position of the weight,Fig. 2, and the lowest number corresponding to its full line position.As the adjustment of the weight thus determines the rate of speed of theoscillations of the pendulum and the shaft it will be obvious that thespeed at which the tapper c vibrates will correspond. At the right handside of the frame L I secure a bracket f which forms a bearing for ashaft f extended through the front plate a of the casing a, said shafthaving fixedly secured to it a disk f Fig. 2, hava peripheral groove fthe length of the circumference of the disk being equal to the totaldistance through which the weight 6 can be moved longitudinally upon thependulum rod e, so that one revolution of the disk in the direction ofarrow 10, Fig. 2, will move the weight from full to dotted lineposition.

A flexible connection f such as a silk cord, is attached at one end tothe weight and at the other end to the periphery of the disk within thegroove as at J, so that by turning the disk in the direction of arrow10, Fig. 2, the connection f will be wound up in the groove, raising theweight a distance depending upon the extent of angular movement of thedisk. The connection f leads up from the weight 6 to and over a smallgrooved guide sheave f rotatably mounted on the shaft b ,'as hereinshown, and thence passes to the disk f a guard f 6 attached to the frameL overhanging the connection close to the disk and preventing theconnection from jumping out of the disk.

The shaft f at the exterior of the casing has secured to it a hand orpointer Fig. 1, the hub of which is provided with an enlarged end f bywhich the pointer and shaft can be turned conveniently to effect angularadjustment of the disk f the dial a being concentric with the shaft. Itwill now be understood that by turning the pointer to any given point ofthe dial more or less of the connect-ion f X will be let off or takenup, correspondingly adjusting the weight e and causing the pendulum andthe tapper c to be vibrated at a rate of speed corresponding to thepoint selected. The dial is graduatedin a peculiar manner, the twelveindicating marks from 1 to 12, Fig. 1, each denoting that if the pointerf is set opposite the same the number of vibrations of the tapper will 91 on the dial the tapper is vibrated at the speed of the beat of thecombined tones of F and. Gt] if properly tuned, a minor third, and soon.

In Fig. 3, a larger view of the dial, the graduations'from 1 to 12 haveindicated adj acent thereto the pairs of notes to be struck by the tunerwhen testing his work, and for a setting of the pointer to eachgraduation there is a corresponding variation in the speed of thevibrations of the tapper. Consequently, by moving the pointer from oneto another graduation the tuner tests his work and can tell at any pointjust where he has made an error. To prevent a continuous rotation of thedisk f I put a stop-pin 30 Fig. 1 between the graduations 1 and 12, inthe path of the pointer, and when the instrument is not in use thepointer is left at 12, and moved to graduation or rate 1 when starting.As it is neither necessary nor desirable that the tapper shall soundcontinuously I provide a detent, herein shown adapted to be swungagainst the pendulum, to press the same against the left hand sidewallof the casing, viewing Fig. 1. A thumbpiece 9 see Fig. 1 outside theplate a and fast on the fulcrum 9 serves to turn the detent against thependulum, to stop it, or into inoperative position to release thependulum, as in Fig. 2. The detent is shown by dotted lines in itsoperative position in Fig. 1.

It will be understood that by arranging the mechanism so that the lowestand highest speeds of the sounding instrumentality will correspond tothe speeds of the tremolos indicated at 1 and 12 respectively on thedial the indices for the intermediate tremolos can be readily positionedon the dial, so that all the tuner has to do is to set the pointer tothe desired indication on the dial and compare the vibrations of thetapper with the beat of the corresponding notes struck on the piano.

The instrument is simple, convenient, easily operated and readilyunderstood, and it is of the greatest assistance in training the ear ofthe tuner in learning the art, so that he soon obtains a clearperception of the vibrations between the intervals of the temperamentand can recognize them readily.

Having fully described my invention, what I claim as new and desire tosecure by Letters Patent is 1. In apparatus of the class described, asounding board, a cooperating tapper, a spring motor operativelyconnected with and to vibrate the tapper, a speed regulator comprising amember fixedly connected with and oscillating in unison with the tapperand a weight longitudinally adjustable on said member, and manuallyoperated means to at will change the position of the weight upon heoscillating member, to thereby increase or decrease the oscillatoryspeed of such member and the vibrations of the tapper.

- 2. In apparatus of the class described, a spring-motor, an escapementtherefor, a pendulum and a tapper fixedly connected with saidescapement, a weight freely movable on the pendulum toward and from itsfulcrum, a sounding board with which the tapper cooperates, a manuallyrotatable disk, and a flexible connection between the weight and theperiphery of the disk, whereby rotative movement of the latter in one orthe other direction will raise or lower the weight and vary the speed ofvibration of the pendulum and tapper.

3. In apparatus of the class described, a spring-motor, an escapementtherefor, a pendulum and a tapper fixedly connected with saidescapement, a weight freely movable on the pendulum toward and from itsfulcrum, a sounding board with which the tapper cooperates, a manuallyrotatable disk, a flexible connection between the weight and theperiphery of the disk, rotation of the latter changing the position ofthe weight and thereby increasing or decreasing the vibratory speed ofthe tap per, a pointer fixedly connected with and to turn the disk, anda fixed dial concentric with the pointer axis and having thereon ascale'indicating different speeds of vibration in accordance with apredetermined plan, whereby manual setting of the pointer to a givenindication causes the vibration of the tapper at the speed denoted bythe indication.

4. In apparatus of the class described, a vibrating tapper and asounding board with which it cooperates, a spring-motor for the tapper,speed regulating means for said motor, including a pendulum having anadjustable weight, a speed-indicating dial, a manually movable pointercooperating therewith, and means operated by setting of the pointer toadjust the position of the pendulum weight and cause the tapper to bevibrated at a speed corresponding to the selected indication on thedial.

5. In apparatus of the class described, a vibrating tapper and asoundingboard with which it cooperates, a spring-motor for the tapper,speed regulating means for said motor, including a pendulum having anadjustable effective length, a dial indicating speed vibrationscorresponding to a predetermined series of tremolos, a manually movablepointer cooperating with the dial, and means operated by setting of thepointer to adjust the effective length of the pendulum and cause thebeats of the tapper on the sounding board to accord with the selectedindication on the dial.

6. In apparatus of the class described, a tapper and a sounding boardwith which it cooperates, mechanism to vibrate the tapper,

a dial having indications thereon denoting certain speeds of vibration,and manually controlled means to cause the tapper to strike the soundingboard at a rate corresponding to any selected indication on the dial,said means comprising a rotatable pointer cooperating with the dial, apendulum having a longitudinally movable weight, and a conneetionbetween the weight and the pointer, to position the weight on thependulum in accordance with angular movement of the pointer.

7. In apparatus of the class described, a spring-motor, an escapementtherefor, a pendulum and a tapper fixedly connected with saidescapement, a weight freely movable on the pendulum toward and from itsfulcrum, a sounding board with which the tapper cooperates, aperipherally grooved rotatable disk, a guide-sheave concentric with thefulcrum of the pendulum, a cord passed over the sheave and secured atits ends to the weight and grooved periphery of the disk, respectively,a pointer fixedly connected with and by which the disk may be rotated,to raise or lower the Weight, and a dial with which the pointercooperates, said dial having a scale of speed vibrations whereby thesetting of the pointer causes the pendulum and tapper to vibrate at anindicated speed.

8. In apparatus of the class described, a spring-motor, an escapementtherefor, a pendulum and a tapper fixedly connected with saidescapement, a Weight freely movable on the pendulum toward and from itsfulcrum, a sounding board with which the tapper cooperates, and means tovary the speed of vibration of the pendulum and tapper, said meansincluding a rotatable, peripherally grooved disk the length of Whosecircumference is equal to the total movement of the weight, a flexibleconnection between the latter and the grooved periphery of the disk, anda pointer attached to and by which the disk is given a predeterminedangular movement.

9. In apparatus of the class described, a sounder, a motor to actuateit, an index graduated to indicate various rates of vibration of thesounder according to a predetermined scale, and means,including amanually positioned pointer cooperating with the index, a pendulum, anda Weight movable thereon by a change in position of the pointer, tocause the vibrations of the sounder to pointer is stopped.

10. In apparatus of the class described, a vibrating tapper a motor toactuate it, a dial having indications thereon corresponding to thevarying rates of speed of the tremolos, and means, including amanually-positioned pointer, a pendulum, a weight movable thereon, and aconnection between the Weight and the pointer, to move the weight by achange in the position of the pointer, to vary the speed of vibration ofthe tapper to correspond with that of the tremolo indication at whichthe pointer is set.

11. In apparatus of the class described, a sounding board, a cooperatingtapper, a spring-motor operatively connected with and to vibrate thetapper, a speed regulator comprising a member oscillating in unison withthe tapper and a weight longitudinally adjustable on said member,manually operated means to at will change the position of the weightupon the oscillating member, to thereby increase or decrease theoscillatory speed of such member and the vibrations of the tapper, and adetent to cooperate with said member and retain the same from movement.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing Witnesses.

CHAS. P. DOLAN.

Witnesses:

ELIZABETH R. MORRISON, BERTHA F. HEUsER.

